Feature: Expand all towns in the scenario editor (#10215)

src/widgets/town_widget.h

@@ -49,6 +49,7 @@ enum TownFoundingWidgets {
 	WID_TF_NEW_TOWN,          ///< Create a new town.
 	WID_TF_RANDOM_TOWN,       ///< Randomly place a town.
 	WID_TF_MANY_RANDOM_TOWNS, ///< Randomly place many towns.
+	WID_TF_EXPAND_ALL_TOWNS,  ///< Make all towns grow slightly.
 	WID_TF_TOWN_NAME_EDITBOX, ///< Editor for the town name.
 	WID_TF_TOWN_NAME_RANDOM,  ///< Generate a random town name.
 	WID_TF_SIZE_SMALL,        ///< Selection for a small town.